<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div{
            width: 800px;;
            margin: 100px auto;
        }
        ul {
            list-style: none;
            float: left;
            width: 75px;
            height: 20px;
            margin-left: 10px;
            background-color: lightpink;
            cursor: pointer;
    
        }

        ul li{
            border:1px solid red;
            text-align: center;
            margin-left: -40px ;
            padding: 10px;
            display: none;
        }
        ul li:hover{
            background-color: red;
        }
    </style>

</head>
<script src="../js/jquery.min.js"></script>

<body>
    <div>
        <ul>
            微博
            <li>私信</li>
            <li>评论</li>
            <li>@我</li>
        </ul>
        <ul>
            微博
            <li>私信</li>
            <li>评论</li>
            <li>@我</li>
        </ul>
        <ul>
            微博
            <li>私信</li>
            <li>评论</li>
            <li>@我</li>
        </ul>
        <ul>
            微博
            <li>私信</li>
            <li>评论</li>
            <li>@我</li>
        </ul>
    </div>
</body>

<script>
   $(function(){
       $("ul").mouseover(function(){
           console.log(this);
           $(this).children().show()
       })
       $("ul").mouseout(function(){
           console.log(this);
           $(this).children().hide()
       })
   })
</script>
</html>